In this research, we used the von Bertalanffy curve for the development of a simulation model of the growth of captive marals or Caspian Red Deer (Cervuselaphussibiricus). The data used in this study was from 18 male marals of Russian (n=9) and Kazakh (n=9) origin, managed under similar conditions, and measured for body weight during their growth at 9, 18 and 24 months. The curve results provided a=219.2 and c=0.163 for the"standard" Bertalanffy model, and a=194.5 and c=0.166 for the Levenberg-Marquardt model. The Akaike Information Criterion was clearly lower in the latter model (17,751) than in the"standard" one (45,652) but there were differences between the obtained and estimated weights. There were no differences in growth between Russian and Kazakh animals, and studied marals did not reach their full growth (i.e. the asymptotic level) by 2 years of age, although theoretically stags are ready to mate at 2430 months of age. Poor feeding of stags in early life or during the antler-growing period can decrease antler production by 1020%, so if the lack of asymptotic level indicates a deficiency in antler production, antler production is below the potential level, probably due to poor nutrition.